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Saccades are assessed by having the patient move his or her eye quickly to a target at the far right, left, top and bottom. This tests for saccadic dysfunction whereupon poor ability of the eyes to "jump" from one place to another may impinge on reading ability and other skills, whereby the eyes are required to fixate and follow a desired object.
Waters' view can be used to best visualise a number of structures in the skull. Maxillary sinuses. Frontal sinuses, seen with an oblique view. Ethmoidal cells. Sphenoid sinus, seen through the open mouth. Odontoid process, where if it is just below the mentum, it confirms adequate extension of the head.
The base of skull, also known as the cranial base or the cranial floor, is the most inferior area of the skull.
A myopic individual can see clearly out to a certain distance (the far point of the eye), but objects placed beyond this distance appear blurred. [16] [25] If the extent of the myopia is great enough, even standard reading distances can be affected. Upon routine examination of the eyes, the vast majority of myopic eyes appear structurally ...
Pinhole glasses, also known as stenopeic glasses, are eyeglasses with a series of pinhole-sized perforations filling an opaque sheet of plastic in place of each lens. Similar to the workings of a pinhole camera , each perforation allows only a very narrow beam of light to enter the eye which reduces the size of the circle of confusion on the ...
Yoked prism can move the image away from primary gaze without the need for a constant head tilt or turn. [1] Prism correction is measured in prism dioptres. A prescription that specifies prism correction will also specify the "base". The base is the thickest part of the lens and is opposite from the apex.
In glasses with powers beyond ±4.00D, the vertex distance can affect the effective power of the glasses. [4] A shorter vertex distance can expand the field of view, but if the vertex distance is too small, the eyelashes will come into contact with the back of the lens, smudging the lens and causing annoyance for the wearer.
Using a phoropter to determine a prescription for eyeglasses. An eyeglass prescription is an order written by an eyewear prescriber, such as an optometrist, that specifies the value of all parameters the prescriber has deemed necessary to construct and/or dispense corrective lenses appropriate for a patient.